1. Field of Invention
The present invention relates to modulators, and more particularly to an improved spread spectrum BPSK, Binary Phase Shift Keying, Modulation system designed for providing gain, low cost and suppressed carrier output, as well as compatibility with CMOS low power logic modulation drive circuitry.
The present system teaches a new, superior, and less costly BPSK modulator than that contemplated by the prior art, providing a less complicated system while outputing increased gain over prior art modulators.
2. Prior Art and General Background
Previous spread spectrum BPSK modulators required conventional balance mixers to produce carrier suppression. These conventional modulators utilized either 1) a complex transistor array in conjunction with a transformer tunable with a potentiometer or 2) two center tapped transformers and four diodes, which arrangement required a high level drive circuit to modulate it, typically +7 to +15 dBM.
Besides the greater expense, increased complexity thereby contributing the probability of failure, and incompatibility with low power -10 dB CMOS logic drive circuitry, the prior art modulators typically produced on the order six dB of signal loss, resulting in considerably less satisfactory overall performance when compared to the present invention.